A alone can complete a task in 3 days and B alone can complete the same task in 6 days. In how many days can A and B complete it together?

6 1 3 2

2

A = 3 days, B = 6 days, ⇒ Time required by A + B to complete the work = \(\frac{6}{2+1}\) = \(\frac{6}{3}\) = 2 days,    ..(\(\frac{Work}{Efficiency}\) = Time)